Loud speaker and other sound-receiving, sound-reproducing, or soundtransmitting apparatus



Jan. 25, 1927.

R SOUND 2 Sheets-Sheet l A. H. MIDGLEY ND RECEIVING, SOUND REPRODUCING, 0 TRANSMITTING APPARATUS Flled July 6 1925 Human-" 1;

LOUD SPEAKER AND OTHER SOU Jan. 25, .1927.

LOUD SPEAKER AND OTHER SOUND TRANS F'il H. MIDGLEY RECEIVING, SOUND REPRODUCING, OR SOUND G APPARATUS 516, 1925 2 Sheets-Sheet 2 II I M li

Patented Jan. 25, 1927.

UNITED STATES PATENT OFFICE.

ALBERT HENRY MIDGLEY, OF UXBRIDGE, ENGLAND.

LOUD SPEAKER AND OTHER SOUND-RECEIVING, SOUND-REPRODUCING, OR SOUND- TRANSMITTING APPARATUS.

Application filed July 6, 1925, Serial No. 41,722, and in Great Britain July 26, 1924.

This invention comprises improvements in or connected with loud speakers and other sound-receiving, sound-reproducing, or sound-transmitting apparatus.

The principal object of. this invention is to improve the production of sound by loud speaking telephones, gramophones and the like and to obtain therefrom greater purity of sound reproduction with absence of false tones and ability to obtain desired effects in the character of the reproduction.

According to this invention, the aperture in the cap or cover, which is in proximity to the diaphragm of a loud speaker or other 16 sound receiving or sound-reproducing apparatus, is furnished with a lip or annular projection extending towards the diaphragm and adapted for being treated in the same manner as an organ pipe, namely by shap- 20 ing or roughening or serrating it, or covering it with appropriate material according to the quality or character of the reproduction desired. The lip may be formed with flat or curved surfaces and a cross section thereof may show either an acute or an obtuse angle. The cover or support from which the lip depends may be flat, or it may be bellied or curved in cross section with either concave or convex curvatures. The

invention further provides for the adjustment of the lip towards or from the diaphragm and such adjustment may be efiected by adjustably mounting the cap or cover on which the lip is formed or mounted, or by adjustably supporting a tubular device having one extremity situated near to the diaphragm and constituting the lip. By adjusting the lip towards the diaphragm, the lower harmonics become more pronounced in the reproduction and this adjustment is,

in fact, comparable with the raising or lowering of the mouth of an organ pipe and affects the harmonics in the same manner.

Not only is the distance of the lip from the diaphragm of importance but so also may be the volume of the space enclosed between the diaphragm and the cap or cover on which the lip is mounted. This volume may be altered to suit requirements by adjustably mounting the cap or cover as aforesaid and as will be hereinafter explained.

In order to enable the invention to be readily understood, reference is made to the M accompanying drawing, illustrating suitable practical examples of embodiments of the invention, in which drawing Figure 1 is a perspective view of the base portion of a loud speaker, a portion of the cover being broken away in order to disclose the telephone and the improved lip formation on the interior of thecover.

Figure 2 is a central vertical section of a loud speaker base similar to that seen in Figure 1 but showing a modified construction of cover and lip formation.

Figure 3 is a central vertical section of a cover with an integral lip formation, this cover being adjustably mounted for the purposes hereinafter described.

Figure 4.- is a central vertical section of a modification in which the lip device is vertically adjustable in the cover towards and from the diaphragm,

Figure 5 is an elevation of the tubular member providing the lip device in Figure 4, and v Figure 6 is a view, as seen from the right hand of Figure 4, of the spigot and top portion of the cover.

Referring to the Figures 1 and 2 in the drawing, a is the base of a loud speaker containing a construction of telephone which is not concerned with the present improvements and which does not require to be described in this specification, suflice it to say that b is the diaphragm which is caused to vibrate by the magnet poles c. The diaphragm b is covered and held in place by a cover d formed or fitted with the usual spigot device 6 for the fitting on of a horn which is not shown in the drawing and which may be of any desired shape and construction. The inner end of the spigot device 6, when inserted into the cenn5 tral aperture in the cover (6 as shown, extends so far-as to form a lip projection f at the inner surface of the cover (Z. This lip may receive various formations and in bellied at g with a curvature presenting a concavity towards the diaphragm b. This curvature may merge into another curve at it presenting a slight convexity towards the diaphragm, and there may be a further curve at j presenting aslight concavity towards the peripheral portion of the diaphragm. Such curvatures may be adopted for the cover d as may be suitable for the nature of the sound production desired in given circumstances. As will be appreciated from an examination of Figure 2, it is desirable that the outer surface of the lip f should be more or less tangential or should more or less merge into the curvature imparted to the interior of the central portion of the cover (6'. The edge ot the lip may be roughened or serrated as at igs. 1, 2, 4, 5" and 6 for obtaining certain tonal efitects, or it may as indicated at Z: Fig, 3 be covered with charnois leather or with a thin layer of india rubber or the like for obtaining other tonal effects, this practice being similar to that which is followed in connection with the voicing of organ pipes.

in the constructions illustrated in Figures 1 and 2, the covers cl are fixedly mounted so that the volume of the space enclosed between such cover and the diaphragm Z) is always approximately the same. In Figure 3, it is possible to alter thisvolume by screw- I101 the cover d" up or down on the cylindrica? body of the casing, a fine screw threading beingindicated at it for the purpose. Also, instead of the lip f and spigot 6 being a separate piece which is fitted into the cover as in Figures 1 and 2, these parts are integral formations on the cover cl. In any event, with a fixed mounting of the lip f on the cover (i any adjustment of the cover d for altering the volume of the enclosed space as aforesaid, will also effect an alteration of the distance between the edge of the lip 7' and the diaphragm b.

In Figured, a cover (Z adapted to be fixed to the base a is shown, but an adjustable cover (Z may be used instead. The feature of the modified construction in Figure 4. is that the lower extremity of a vertically adjust-able tubular member 7" provides the lip formation 7 so that by elt'ecting vertical adjustment of the member f the distance ol? the lip from the iliaphragiu is altered. The tubular member may have a hole Z formed in it at a suitable point in its length see-v Figure 5. An adjusting ring m is revolubly fitted 011 the spigot c and a radial screw threaded hole is formed in the thickness. of this ring. Finally, an inclined or helical slot a is formed in the spigot e, seen in Figure 6. The parts are assembled so that the hole Z, the slot n and the screw threaded hole in the ring m are in register, whereupon an elongated screw pin 7) is screwed through the hole in the ring or, the plain portion of the pin passing through the slot at and the hole Z and extending across the bore of the tubular member 7' when the screw is loosened, the ring he can be turned and such turning will elevate or depress the tubular member owing to the action of the inclined slot n on the pin 7). When the desired relation between the lip f and diaphragm b has been thus secured, the screw pin is screwed in tightly and the end of the pin 7) abutted against the inner wall of the tubular member f" causes the parts to be secured in the position towhich they have been adjusted.

1. A'telephone device comprising a diaplrragm, a cover having a sound aperture and presenting a concavity towards the diaphragm, a lip device on said cover around said aperture and extending towards the diaphragm, and tone modifying means on saidv lip.

2. A telephone device comprising a telephone vibrator, a coverha-vinga sound aperture and presenting a concavity towards the vibrato-r, a lip on said cover surrounding said aperture and extending towards the vibrator, and an adjustment operative to vary the distance between said lip and said vibrator.

A telephone device comprising a vibratory element, a cover presenting a concavity towards the vibratory element and having a sound aperture, a tubular lip device adj ust-ably fitted to said cover in said aperture, and adjustment means operative on said lip device to vary the distance between said de vice and said vibrator.

ALBERT HENRY MlDGLlQ Y. 

